Location: Functional Foods ResearchTitle: Physical properties of beeswax, sunflower wax, and candelilla wax mixtures and oleogels
Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2019
Publication Date: 8/29/2019
Citation: Winkler-Moser, J.K., Anderson, J., Felker, F.C., Hwang, H.-S. 2019. Physical properties of beeswax, sunflower wax, and candelilla wax mixtures and oleogels. Journal of the American Oil Chemists' Society. 96(10):1125-1142. https://doi.org/10.1002/aocs.12280.
Interpretive Summary: There is increased interest in using natural waxes as alternatives to partially hydrogenated oils and saturated fats in foods. Using relatively low concentrations (0.5-5%), natural waxes are able to form crystalline networks, or oleogels, which bind liquid oil to form a continuous semi-solid. Each natural wax is different in its composition, and this strongly affects the physical properties of these oleogels, such as the melting point and the firmness. While much is known about the properties of oleogels made with a single wax component, there is little information about how waxes with different compositions will interact and how the interaction between waxes in oleogels will affect their physical properties. Therefore, the objectives of this study were to characterize the melting and crystallization properties of binary mixtures of beeswax, sunflower wax, and candelilla wax, along with the physical properties of organogels made with the wax mixtures. Each wax combination had unique melting and crystallization properties and for most wax combinations and ratios of each wax, there was evidence of the contribution of each wax to the crystal morphology of the oleogels. The two major components of beeswax and candelilla wax co-crystallized and co-melted when mixed together. Depending on the ratio of waxes, the oleogels made from these waxes tended to start melting at lower temperatures, while some had a firmer texture than oleogels made from either wax on their own. When beeswax and sunflower wax were mixed, the resulting oleogels were softer in texture. This is likely due to the larger crystal microstructures contributed by beeswax components that appeared to disrupt the network of sunflower wax crystals. Candelilla and sunflower waxes were very different from each other in their composition and the resulting mixtures typically had two crystallization and two melting point curves. Oleogels prepared from these waxes with low ratios of candelilla wax to sunflower wax were very soft, and examination of the crystal morphology showed that the candelilla components caused the sunflower wax to aggregate into large clusters. However, with high candelilla wax to sunflower wax ratios, the resultant gels were in some cases as firm as or firmer than either oleogel on their own, yet had a much better melting profile. These results indicate that the interactions between waxes are each different and have different implications on the properties of oleogels made with them. This research has future implications for designing organogels using combinations of materials to achieve desirable physical properties that can be modified for different applications.
Technical Abstract: Interest in natural waxes as alternatives to partially hydrogenated oils and saturated fats as oil structuring agents has increased in the past decade. Each natural wax is uniquely composed of long-chain hydrocarbons, long chain fatty acid alcohol esters, long chain alcohols, or mixtures of these and other components in various proportions. The composition and purity of each wax type plays a determining role in the physical properties of oleogels, such as the level of wax needed to bind oil, the melting and crystallization properties, and the firmness and rheological properties. However, only a few studies have evaluated the interactions between waxes from different sources, and how these interactions impact the properties of oleogels. Therefore, the objectives of this study were to measure the melting and crystallization properties of binary mixtures of beeswax, sunflower wax, and candelilla wax, along with the thermal properties, crystal morphology, and firmness of oleogels made with the wax mixtures. Each wax combination had unique thermal properties, but beeswax: candelilla wax mixtures were most interesting because the melting point of mixtures ranging from (w:w) 20:80 to 90:10 beeswax: candelilla wax was lower than either pure component (63.7 °C and 64.9 °C, respectively). Organogels made with beeswax:candelilla wax at several ratios also had lower melting and crystallization temperatures and higher firmness compared to the pure wax organogels. These results have future implications for designing oleoogels using combinations of materials to achieve desirable physical properties that can be modified for different applications.